1. Field
Example embodiments relate to magnetoresistive structures, magnetic random-access memory devices including the same, and/or methods of manufacturing the magnetoresistive structure.
2. Description of the Related Art
As thin-film deposition technology and surface processing technology in a high-vacuum state have rapidly developed, it has become possible to precisely grow a magnetic thin film within a thickness of several nanometers (nm) to be used in the manufacture a magnetic random-access memory device. The thickness of the magnetic thin film is grown so as to match an exchange interaction distance between spins of a magnetic random-access memory device. Accordingly, various phenomena have been discovered which were not observed from a magnetic material in a bulk form, and thus these various phenomena are being applied to home appliances and industrial components, for example, a magnetic recording head or a magnetic random-access memory (MRAM) for recording information in an ultra high-density information storage apparatus.
A magnetic random-access memory device is a memory device which stores data by using a resistance change in a magnetic tunneling junction (MTJ), which is a magnetoresistive structure. The magnetoresistive structure is formed to have a pinned layer and a free layer. A resistance of the magnetoresistive structure varies with a magnetization direction of the free layer. For example, if a magnetization direction of the free layer is the same as that of the pinning layer, the magnetoresistive structure may have a low resistance value. If a magnetization direction of the free layer is opposite to that of the pinning layer, the magnetoresistive structure may have a high resistance value. As such, if the magnetoresistive structure of the magnetic random-access memory device has a low resistance value, the low resistance value may correspond to, for example, data ‘0’. If the magnetoresistive structure of the magnetic random-access memory device has a high resistance value, the low resistance value may correspond to data ‘1’.
It is necessary to implement a high magnetoresistance (MR) ratio, so as to achieve a magnetic random-access memory device which has excellent characteristics. To achieve this, a lot of research is being conducted.